A gas turbine engine generally includes a fan and a core arranged in flow communication with one another. Additionally, the core of the gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided from the fan to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air using one or more fuel nozzles within the combustion section and burned to provide combustion gases. The combustion gases are routed from the combustion section to the turbine section. The flow of combustion gasses through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere.
More specifically, the fuel nozzles function to introduce liquid fuel into an air flow stream such that the liquid fuel may atomize and burn. Additionally, staged fuel nozzles have been developed to operate with relatively high efficiency and operability. In a staged fuel nozzle, fuel may be introduced through two or more discrete stages, with each stage being defined by an individual fuel flow path within the fuel nozzle. For example, at least certain staged fuel nozzles include a pilot stage that may be operable continuously, and a main stage that operates at, e.g., high power levels.
With certain embodiments, the main stage may include an annular main injection ring having a plurality of fuel injection ports which discharge fuel through a round centerbody into a swirling mixer airstream. When the main stage is not in use, it may be beneficial to purge at least a portion of the fuel therein such that the fuel does not increase in temperature and begin to coke. Accordingly, a fuel nozzle with one or more features enabling the main stage of the fuel nozzle to purge at least a portion of the fuel therein would be useful.